Objective:

• to detect amino acid gauanidium group [R-NH-C= (NH2)2+-NH2]. i.e arginine

Principle of Sakaguchi test:

This test is specific for arginine because this reaction is given by guanidinium compound. The arginine reacts with α – napththol and an oxidizing agent  such as bromine water or sodium hypochlorite/sodium hypobromite to give a red colored product. The other guanidinium containing compounds other than amino acid also give this reaction.

Reagents:

• test solution: 1 % arginine, 1 % glycine, 5 % egg white (albumin)
• 1 % α naphthol in alcohol
• Sodium hypochlorite
• 1 % urea solution
• Dry test tubes
• Pipettes

Procedure of Sakaguchi test

1. Take 1ml test solution in dry test tube.
2. Similarly, take 1ml distilled water in another test tube as control.
3. Add 2 drops of α naphthol and mix well.
4. Now add 2ml sodium hypochlorite to all test tubes.
5. Immediately add 1ml of urea solution to establish the red complex formed.

Result interpretation:

• Positive sakaguchi test: Red color ( Arginine)
• Negative sakaguchi test: no red color ( glycine, albumin)

Sakaguchi test: Objective, Principle, Reagents, Procedure and Result

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